A novel approach has been developed to measure the voltages of individual batteries used in electric vehicle (EV) battery packs using a unique selective battery measurement system. This system consists of a voltage measurement circuit that measures battery voltages using a set of electromechanical relays connected in a matrix formation. A 16-bit microcontroller was used for controlling the operation of the relay matrix circuit. The system was designed for a pack of 12 series connected 12 V-dc lead-acid batteries. The proposed approach was found to be compact and is universal one that can be used for any type of battery. Moreover, the method was very effective and produced good accuracy. In fact, test results over a wide temperature range of --20 to +40 C-o indicated that the method is very precise with voltage fluctuations less than +/- 30 mV. (C) 2006 Elsevier B.V. All rights reserved.